Telephone-exchange system.



E. R. LUNDIUS.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 3 I918.

Patented Mar. 11,1919.

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ERIC R. LUNDIU'S, OF BROOKLYN, NEW YORK, ASSIGNOR TO"WESTERN' ELECTRICCOMPANY, INCORPORATED, NEW YORK, N. Y., A CORPORATION OFNEW YORK. i

TELEPHONE-EXCHANGE, SYSTEM;

To all whom it may concern:

Be it known that I, E1210 R. Lmvoros, a

citizen of the United States, residing at ing purposes, and which'areequipped with I trunk circuits extendlng to privatebranch exchanges,chief operators desks and like positions.

In systems, of this type employing trunk circuits extending from aswitchboard posi-' tion to a chief operato'rs or information operatorsdesk and cooperating at the switch: 7

' .board position with an automatic ringing link circuit, it is usual tocause the disconnection of ringing current from the trunk circuit uponconnectionbeing made therewith at the answering or incoming end.

' There is usually considerable disturbance in the talking circuitattending the'disconnection of the ringing current and the subst tutionof the direct current therefor, which, if

the answering operators receiver be connect edto the talking circuit,produces very severe clicks in the receiver. It is an object of thisinvention to provide a system of this character in which the receiver ofthe answering operator is not connectedwith the talking circuit untilafter ringing current has been disconnected and direct currentsubstituted therefor, thereby practicallyeliminating all disturbance inthe receiver of the answering operator. It is'also an object of I thisinvention'to provide improved slgnaling means for systems of thischaracter.

In accordance with this invention the ringingcurrent is automaticallyconnected with the trunk circuit upon the connection of the link circuittherewith and upon connection being madewith the trunk circuit-atthe'incoining end, apparatus respondsto con-V nect across the trunkcircuit a low impedance bridge for causing the disconnection of theringing current from the trunk circuit, after which the normally opentalking con ductors of the trunk circuit are closedtoex- V tend thetalking circuit to thedesk; x l

' For amorecomplete understanding of this Specification of LettersPatent.

with the accompanying drawing Patented Mar. 11,1919.

Application filed May 3, 1918. Serial No. 232,269.

invention, reference should be had to the following descriptionconsidered in connection one embodiment thereof. p j

There is shown in the 'drawingan'auto 'matic ringing link. circuit Alocated at a switchboard position, from which a trunk circuit B'extendsto an operators desk,'or other switchboard position; At the desk thereis located a cord circuit C, by means of which connection. may be-madewith the in- 7 coming end of the trunk circuit. The apparatus shown tothe left" of the dotted line illustrating 11 is loc'atedat theswitchboard 'X, and

that located to the right of the dotted line 11 may be located at thedeskvor second switchboard'Y.

The nature of this invention is such that it is thought that it will beclearlyun'derstood from a'description of the operation of thesystemdisclosed in the drawing and it will be so described.

The originating operator desiringv to es tablishv a connection by way ofthe trunk circuit with the desk operator,inserts plug 5 of the cordcircuitA into jack 6 of the trunk circuit B, whereupon lamp 7 lights andrelays 8 and 9 operate over a circuit 7 from battery'through the lamp 7,winding of relay 8, sleeve contacts ofthe plug 5 and the jack 6, contact10 of relay 11, winding of-relay 9 and contact 12 of relayll to ground.Relay 8, in operating, causes the operation of'ringing relay 13 over acircuit 7 from battery throughresistance 14, winding of ringing relay13, normal contact ofrelay '15, c ontact of tripping relay 16 andthecontact'ofrelay 8 to ground. The operation of ringing relay 15 connectsa source of ringing current'l'? through thewinding of the trip.- pingrelay 16 to the trunk circuit B. The

operation of relay 9 causes the lighting of lamp 18 over a circuit from.battery through the lamp 18, contact 19 of relay11 and-the I contactofrelay 9 to-ground.

The deskoperatorobserving the lighted condition of'the lamp 18 insertsplug 25 of the cord circuit A intoijack 26 of the trunk circuitB,whereupon the lamp 27 isilighted and relay 28 operated overa circuitfrom battery through the-lamp 27 resistance 29, sleeve contacts ofthedplug 25"and the jack 26, lower winding of relay 2 8 and contact 30.of relay 31 togroundl .Relay28, in o erat- 1 Y ing, short-circuitscondenser'32 and connects of the trunk circuit B; The right and lefthandwindings of this retardation coil 33 are of low impedance, while themiddle winding is of high impedance. The. tripping relay 16 will notoperate when the three wlndin'gs" 0f the retardation coil 33 areconnected in series therewith. Relay 28, in operating, also causes theoperation of relay 11 over a circuit from battery through the lamp 7,Winding of relay 8, sleeve contacts of the plug 5,

the jack 6, contact 34 of relay 28 and-the Winding of relay 11 toground. .Relay" 11, in operating, opens'the circuit of and efiacesthelamp 18, removes relay 9 from the sleeve conductor, therebydeenergizing this relay 9, andfby the closure of its contact 35,connects relay 9 in ,parallel with the middle or high impedance windingof the retardation coil 33; The closure ofcontact 36 of relay 11establishes a locking circuit therefor, thereby rendering this relayindependent of the'condition of relay 28. Theconnection of relay 9 inparallel with the high impedance wind ing of the retardation coil 33lowers the impedance'of the bridge to such an extent that the trippingrelay 16 operates.

The tripping relay 16, in operating, removes thefshort circuit from thewinding of the relay 15, which thereupon operates, locks up andestablishes a short, circuit for the ringing relay 13, which isthereupon deenergized to disconnect the source of ringing current fromthe trunk circuit B. Ringing relay 13 in closing its normal contactscon-' nects a source'of dlrect current with the talkin conductors of thetrunk circuit.

elay 9 is responsive to direct current but is non-responsive to-ringingcurrent. That is, while there isa partial attraction of the armature ofrelay 9 when its winding is traversed by ringing current, thisattraction is not sufficient to permit the continued 'closure of itscontact. Upon the disconnection of ringing current from the trunkcircuit B,

'a source of direct current is substituted therefor so that the relay 9then I operates over a circuit from battery through the winding, ofsupervisory relay 40, lower normalcontact of ringing relay 13, ringcontacts of the plug 5 and the jack 6, left-hand winding of impedancecoil 33, contact 35'of relay 11, wi nding of relay 9, right-hand windingof retardation coil 33, contact 41 of relay 28, tipcontacts of the jack6 and the plug 5,

' upper normal contact of the ringing relay 13 to ground. Relay 9, inoperating, causes the operation of a slow-release relay 42 over acircuit froln'battery through the normal contact of slow-release relay43, normal contact of relay 44, winding .oiislow-release relay 42,contact 45 of'rela'y 11 and the contact of relayj 9 to ground.v.lRelay'42, in operating,

causes the operation of relay 44 overa cirright-hand alternate contactand winding of relay 44, contact 45 of relay 11 and thecOntact of relay9 to ground. The operation of relay 44 opens the circuit of relay 42,which thereupon releases its armature. Upon the closure of the left-handcontact ofrelay-42, relay 31 operates over a circuit from batterythrough the winding of relay 31, left-hand alternate contact of relay44, left hand contact ,of relay 42, contact 45 of relay 11 and thecontact of relay 9 to ground. Relay 31, in operating, opens its contact30, thereby removing the short circuit from the upper winding of relay28, which increases the resistance in circuit with the lamp 27 to suchan extent that the lamp is efiacedQ Relay 31, in operating, also closesnormally open contacts in the talking conductors of the trunk circuit.Upon the closure of the circuit through supervisory relay '40, thisrelay oper ated, establishing about the lamp 7 a shunt circuit includingresistance 14 for efia'cing the supervisorylamp 7. The originatingoperator may thereupon actuate listening key 46 to connect the telephoneset in circuit. The deskoperator may actuate listening key 47 to connectthe desk operators telephone set in circuit, that is, if thislistening'key 47 circuit, the originatingoperator may resignal the deskoperator by causing the flashing'or intermittentiglowjof the lamp 27.This is brought about by the repeated withdrawal of the plug-5 fromandthe insertion thereof into the. jack 6. 'Upon thewithdrawal of'the plug5 from the jack 6, relays restores all apparatus 9, 11, 44 and'31release their armatures. V,

The release of relay31 closes its contact 30 thereby short-circuitingthe upper windin' of relay 28. The resistance in circuit wit the lamp 27is thereby reduced to suchan extent that the lamplights. The closure ofV the upper and lower normal contacts ofrjelay 3l establish'es a shortcircuitabout each of. the co11densers' '48 and 49, thereby to pro- Vi-dedischarge. Paths i hese condeIiSerS, .S'o' i that when'the normally opencontacts in-tlie talkingconductors are 'closed upon'the sc nt zcti efjqfsi t 3 hr w be no discharge from the condensers over the talkingcircuit. The connecting of these condensers in circuit with the talkingconductors when in their discharged c0nditi0n prevents disturbancein thetalking circuit. The

reinsertion of the plug 5' into the jack 6 causes the operation ofrelays 8 and '9, as before. Relay '8 operates the ringing relay toconnect ringing current with the trunk circuit, and relay 9 may lightthe lamp "18 momentarily but for no longer, for relay 1f operatespractically simultaneously with the operation of relay 9, and in sodoing,

opens the operating circuit of the lamp .18 and the energizing circuitof relay 9. Relay 11, in operating, also connects the relay 9 in shuntof the high impedance winding of the retardation coil 83, thereby tocause the operation of the tripping relay 16 and the consequentdisconnection of the ringing current from the trunk circuit, in themanner hereinbefore described. Relay 9 then operates to energize theslow-release relay 42, whereupon relay 44 is energized and'locked up torelease relay 42. Upon the release of this relay, relay 31 operates inthe manner already described to complete the talking circuit. Each timethe plug 5 is withdrawn from the jack 6, the lamp 27 islighted and theintermittent lighting of this lampserves as a signal to the deskoperator, who,'upon observing the flashing thereof, may actuate thelistening key 47 to connect the telephone set in circuit.

If a calling telephone line (not shown) is connected by way of theautomatic ringing cord circuitA and the trunk circuitB with thedeskoperators cord circuit'O, the desk operator may converse directlywith the calling subscriber. After furnishing to the subscribersuchinformation as is desired, the desk operator may wish to signal the"originating operator. This may be done by the repeated actuation of key50, to cause the flashing or intermittent operation of the supervisorylamp 7 of'the cord'circuit 8. The

actuation of t e key50 by the closure of the upper contact,short-circuits the windings of relay 28, thereby causingthis relay torelease its armatures to open up the direct current bridge of thetalking conductors'which includesretardation coil 33' and relay 9. Su-'pervisory relay 40 thereupon releasesitsarmature to remove the shuntcircuit from about lamp 7. This lamp 7 thereupon-lights. The closure ofthe lower contact of the key 50 energizes the slow-release relay '43,which opens its normal and closes itsaltern'ate'contact. The opening ofthe normal contact of relay 43 prevents the energization of relay 42after relay 44 has'released its armatures,

following the deenergization of 'relay'9. The closure of the alternatecontact'of relay 43 prepares anenergizing-circuit for re1ayf44 which isindependent of the relay 42. I Relay r 9 releases its armature upon theopening of the direct current bridge of the talking con.- ductors, andin so doing, opens the circuits of relays 31 and 44 which thereuponrelease their armatures. The relay 31, in releasing its armatures, opensthe talking conductors of the trunk circuit. Upon the restoration of thekey 50 to normal position, the short circuit is removed from the lowerWinding of relay 28 which thereupon operates, reestablishing the directcurrent bridge ofthe talking conductors. Relay 40 and relay 9 thereuponoperate, the former causing the efi'acement of the lamp 7 and the lattercausing the operation of relay 44. Relay 44, in operating, causes theenergization of relay 31, which removes the shortcircuit of the upperwinding of relay 28 and closes the normally open contacts of thetalkingconductors. Relay 43 being slow to release, maintains itsalternate contact closed after the opening of the lower contact of thekey 50, until the contact of relay 9 is closed. Therefore, relays 28,9,44 and 31 are the only relays which function to control the openingand the closure of the talking conductors while the desk operator issignaling the originating operator. The lamp 7 is llghted each timethekey 50 is actuated, and

the intermittentlighting of this lamp serves erator may hear theoriginating operator an- 'swering and stop the repeated actuation of thekey 50.

What is claimed is:

l. Atelephone exchange system compris: ing a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the Zfirstswitchboard, a source of ringing current, means responsive to theconnection of the llnk circuit with the trunk circuit for with, a linkcircuit at the second switch- *connectinga source of ringing currentthere- V board, a relay responsive to the connection.

of the second link circuitWith the trunk ,circuit, and a low impedancebridge for the trunk circuit'established upon the response of the relayfor causing the disconnection of 1 .the source of ringing current fromthetrunk circuits r ,2. A telephoneexchange system compris-"12 5 ing atrunk circuit having normally open 1 talking conductors extending from afirst to a'second switchboard, a-link circuit at the i firstswitchboard, ais'ource ofjringingcur I :rent,means respons1ve totheconnection of the link circuit with the trunk circuit for connecting thesource of ringing current therewith, a signal control relay in the trunkcircuit responsive to the connection of the link circuit therewith, alink circuit at the second switchboard, means responsive to theconnection of the second link circuit with the trunk circuit forconnecting the signal control relay in bridge of a the talking-.0011-ductors, means in the first link circuit responsive to the connection ofthe signal control relay in bridge of the talking conductors fordisconnecting the source of ringing current from the trunk circuit,means for thereafter energizing the signal control relay over thetalking conductors, and means responsive to the energization of thebridged relay for closing thenormally open talking conductors. p

3. A telephone exchange system con1prising a trunk circuit extendingfrom a first to a second switchboard, a link circuit at the firstswitchboard, a source of ringing current, means responsive to theconnection of the link circuit with the trunk circuit ,for connectingthe source ot ringing current therewith, a signaling device at thesecond switchboard, a relay energized upon the connection of the linkcircuit with the trunk circuit for operating thesignaling device, a linkcircuit at the second switchboard, a relay operating upon the connectionof the second link circuit with the trunk circuit to denergize andconnect the first relay in bridge of the talking conductors, and meansin the, link circuit responsive to the connection of the first relay inbridge of the talking conductors for disconnecting the source of ringingcurrent from the trunk circuit. V V

4:.oA telephone exchange system comprising a trunk circuit havingnormally open talking conductors extending from a first to a secondswitchboard, a link circuit at the first switchboard, a source ofringing current, means responsive to the connection of the link circuitwith the trunk circuit for connecting, the source of ringing currenttherewith, a link circuit at the-second switchboard, a relay connectedin bridge-of the talking conductors upon the-connection of the secondlink circuit with the trunk circuit, means in the first link circuitresponsive to the connection of the relay in bridge of the talkingconductors for disconnecting the source of ringing current from thetrunk circuit, a source'of'direct current connected with the trunkcircuit upon thedisconnection of the source of ringing current for en-'ergizing the bridged relay, and a relayresponslve to the energ zatlonofthe-bridged V relay for closing the normally open talking conductors.

5. A telephoneexchange system comprising a trunk circuit having normallyopen talking conductors extending from a first to a second switchboard,a link circuit at the first switchboard, a source of ringing-current,means responsive to the connection of the link circuit with the trunkcircuit-for connecting therewith the source of ringing current, a signalcontrol relay operating upon connection of the link circuit with'thetrunk circuit, a link circuit at the second switchboard, a relayoperating upon the connection of the second link circuit with the trunkcircuit for releasing and connecting the signal control relay 1n bridgeof the talklng conductors, means 111 theifirst' l nk circuit responsiveto the connection of the of the talking conductor control. relay.

In witness whereof I hereunto subscribe my namethis 27th day of'April,A; D.- 1918.

o ERIC R; LUNDIUS.

7 Copies of this patent may be obtained for five cents each, byaddressing the Commissioner of Patents,

Washington, D. 0.": V V

